Environmental stability, high impact strength, resistance to flame and shock, and low cost are among the most important and desired characteristics for containers such as gun propellant casings.
To achieve strength and to resist flame and shock, however, it is generally necessary to limit or wholly replace casing materials of a high energetic nature, such as felted nitrocellulose casings with low energy polymeric material and to attempt to make up the difference by achieving a higher propellant-packing density.
The use of inert, tough organic compounds such as synthetic resins (U.S. Pat. No. 3,749,023), polycarbonates, polysulfones and blends thereof with polyethylene (U.S. Pat. No. 3,745,924), Polyethylene terphthalate (PET) (U.S. Pat. No. 3,901,153), polyester film (U.S. Pat. No. 4,282,813), or similar polymeric materials, however, are not fully satisfactory as substitutes for nitrocellulose (NC) felting, because of difficulty in carrying out firings without fouling a barrel and gun breach with partly consumed casing. Such smoking residue also presents a serious air pollution and storage problem within the confines of a tank or similar vehicle under buttoned down combat conditions.
Attempts at compromise, such as the use of thin sheets of plastic interspaced between traditional felted nitrocellulose layers (U.S. Pat. No. 3,901,153) have resulted in some improvement in moisture resistance and handling properties, but have not succeeded in adequately addressing case combustion problems.
The present invention substantially increases consumability by increasing the amount of fragmentation and the resulting combustion of a propellant-charged gun propellant casing used in a conventional firing sequence. In addition the practice of this invention obtains a consumable inert propellant casing having improved flame and shock resistance plus increased mechanical durability.